Implementation and efficiency of an automatic peak-purity-control procedure in HPLC-UV-VIS-coupling based on principal component analysis

Development of a rapid and validated stability-indicating UPLC-PDA method for concurrent quantification of impurity profiling and an assay of ipratropium bromide and salbutamol sulfate in inhalation dosage form

The objective of the proposed work was to develop a rapid and new reverse phase ultra-performance liquid chromatographic (RP-UPLC) method for the simultaneous quantification of related impurities of ipratropium bromide and salbutamol sulfate in the combined inhalation dosage form. Herein, the chromatographic separation was achieved on Acquity BEH C18 (100mm×2.1mm, 1.7μm) column by following gradient elution of solvent A as 2mM potassium dihydrogen phosphate with 0.025% of 1-pentane sulphonic acid sodium salt (pH 3.0 buffer) and solvent B as pH 3.0 buffer, acetonitrile and methanol in the ratio of (32:50:18, v/v/v) at a flow rate of 0.3mL/min. The samples were detected and quantified at 220nm. To prove the stability-indicating potential of the method, forced degradation studies were performed using acidic, basic, oxidative, thermal, and photolytic conditions. After sufficient exposure, the resultant solutions were injected and found that all degradants and impurities formed during stress studies were well separated from each other and from the main peak compounds. The performance of the method was validated according to the present ICH Q2 (R1) guidelines. The method has good linearity (r≥0.999) and consistent recoveries were obtained with a range of 91.3-108.8% for all compounds. The % RSD obtained for the precision experiments was less than 5% and also there is a good sensitivity (LOQ≤0.5μg/mL) for all compounds. The intended method proved its applicability and that it can be beneficial to pharmaceutical industries for quick quantification of related impurities and assay in quality control department for analysis of ipratropium bromide and salbutamol sulfate inhalation dosage form.

Single quad mass analyzer coupled UPLC method for impurity profile of Brimonidine tartrate and Timolol maleate: Application in their binary mixture ophthalmic formulation

The main objective of the study is to develop a suitable and rapid UPLC/PDA method by coupling online to Quadrupole Dalton analyzer (QDa), a mass detector for the identification and impurity profiling of Brimonidine Tartrate (BRIM)/Timolol maleate (TIMO) in the ophthalmic formulation. Chromatographic separation was achieved on ethylene bridged hybrid octadecylsilane column having 1.7μm particle size in gradient mode using high pure heptafluorobutyric acid as a buffer (A) and water, methanol, and acetonitrile (B) as mobile phase with a flow rate of 0.3mlmin^-1. Based on the spectral maxima, BRIM and its impurities were monitored at 248nm, and TIMO and its impurities were monitored at 295nm. During evaluation of stress conditions and stability data unknown degradants are observed and identified as m/z 218.01 (DP1) and m/z 390.03 (DP2) using QDa-ESI+ scanning mode technique. The performance of the method was systematically validated according to ICH Q2 (R1) guidelines and the method shown very good sensitivity (≥0.5μg.mL^-1) and linearity (r²≥0.999) with consistent recoveries and less than 5% RSD for all compounds. Hence, the proposed UPLC/PDA/QDa method is a simple, sensitive and comprehensive technique where identification and quantification can be done. It gives for complete impurity profile evaluation of BRIM/TIMO in the ophthalmic formulation during quality control in the pharmaceutical industry.

Hyphenated liquid chromatographic techniques in forensic toxicology

The prerequisite of applicability of hyphenated methods in forensic analysis is the achievement of a stage of "final maturity". In the field of liquid chromatography, HPLC coupled with diode array detection (DAD) seems to fulfill this criterion, whilst the combination with atmospheric pressure ionization mass spectrometry (HPLC-API-MS) is still in a development stage. HPLC-DAD is broadly used as identification tool in forensic and in emergency toxicology. Two main approaches were observed; development of retention index scales for intra-laboratory exchange of data and establishing of databases only for intra-laboratory use. Using these approaches, several databases were established for toxicological relevant substances (illicit and therapeutic drugs and their metabolites, environmental poisons etc.) in biological fluids. Also, complete HPLC-DAD identification systems are commercially available. Further possibility of progress depends on the on-line combination ("triple hyphenation") with other detection methods, preferably API-MS. HPLC-API-MS, both in electrospray (ESI) and atmospheric pressure chemical ionization (APCI) options, underwent dramatic development in the last decade and is reaching its final shape. The method was broadly applied for various groups of toxicologically relevant substances, a lot of them unaccessible for other techniques, including GC-MS. Particularly important was application of HPLC-API-MS for detection and quantitation of active, polar metabolites of various drugs and for analysis of macromolecules. APCI seems to be more useful for analysis of less polar compounds, whereas ESI is particularly valuable for determination of polar, large molecules (e.g., toxic peptides, polar metabolites etc.) Up to now, HPLC-API-MS has been mainly applied for dedicated analyses, but the introduction of APCI or ESI in systematic toxicological screening may be expected in the near future.

Assessment of chromatographic peak purity by means of artificial neural networks

An improved chemometric approach is proposed for assessing chromatographic peak purity by means of artificial neural networks. A non-linear transformation function with a back-propagation algorithm was used to describe and predict the chromatographic data. The Mann-Whitney U-test was used for the concluding the purity of the chromatographic peak. Simulation data and practical analytical data for both pure and mixture samples were analysed with satisfactory results. A prior knowledge of the impurity and the related compound is unnecessary when a slight difference between their chromatogram and spectrum exists. The performance on simulated data sets by this approach was compared with the results from principal component analysis.

Chemometrics in pharmaceutical analysis

Pharmaceutical analysis is undergoing a slow revolution as chemometric principles become increasingly incorporated. This paper reviews some of the more recent advances, with particular focus on spectrophotometry, chromatography and expert systems.